Isocyanate polyolefin prepolymer and preparation method thereof, resin composition containing isocyanate polyolefin prepolymer, packaging adhesive film, solar cell module and application

Abstract

The invention discloses an isocyanate polyolefin prepolymer, a preparation method thereof, a resin composition containing the isocyanate polyolefin prepolymer, a packaging adhesive film, a solar cell module and application, and belongs to the technical field of solar cell packaging materials. The number-average molecular weight of the isocyanate polyolefin prepolymer is 550-20000 g / mol, the viscosity of the isocyanate polyolefin prepolymer at 40 DEG C is 10-5000 Pas, and the isocyanate polyolefin prepolymer comprises unsaturated side groups and unsaturated end groups which are chemically bonded on a carbon chain. The resin composition containing the isocyanate polyolefin prepolymer can be used as a packaging adhesive film of a solar cell module, and can enhance the water vapor blocking capability of the solar cell module and the stability of the solar cell module in the environment.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell encapsulation materials, and in particular to an isocyanate polyolefin prepolymer and a preparation method thereof, a resin composition containing the same, an encapsulation film, a solar cell module, and the application of the grafted polyurethane prepolymer material in the field of solar cells. Background Art

[0002] High-efficiency crystalline silicon solar cells are becoming increasingly mature, such as PERC (Passivated Emitter Rear Cell), TOPCon (Tunnel Oxide Passivated Contact), HJT (Heterojunction with Intrinsic Thin-film), and IBC (Interdigitated Back Contact). These new cells have multiple advantages such as high conversion efficiency, low attenuation, and high bifaciality. Since the silver paste used in these new cells is relatively special, it is easy to produce a potential difference under the action of water vapor, causing corrosion of the paste, which can easily cause a significant decrease in the power generation efficiency of the cell. Therefore, it is necessary to use high-performance barrier materials to encapsulate the cell. After ethylene vinyl acetate copolymer and polyolefin elastomer materials are mixed with silane coupling agents, cross-linking agents, etc., they are cast into films and laminated with photovoltaic cells for encapsulation, which can protect the photovoltaic cells to a certain extent. Due to the cooling crystallization of the encapsulation material, the surface wettability of the encapsulation material and the cell or glass is reduced. When photovoltaic modules are exposed outdoors for a long time, water vapor can easily enter the module from the edge of the glass or the back panel, thereby corroding the cell grid lines and reducing the module's power generation performance.

[0003] At present, medium and low molecular weight olefin polymers or liquid olefin polymers (CN117467050A, CN114933873B, CN117987035A) are developed to alleviate the problem of insufficient wettability of solar cell encapsulation film on the surface of battery cells and glass, and easy penetration of water vapor. These materials contain carbon-carbon double bonds in the side groups, which can be grafted with the matrix resin EVA (ethylene and vinyl acetate copolymer, Ethylene Vinyl Acetate Copolymer) or POE (Poly Olefin Elastomer, polyolefin elastomer). However, unmodified olefin polymers often have low polarity and poor compatibility with crosslinking agents, coupling agents and other additives. On the other hand, liquid olefin polymers are inconvenient to use in the process of mixing, processing and casting. Medium and high molecular weight olefin polymers (CN116769425A, CN104081540B, CN112437787A) such as low-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-octene copolymer, ethylene-hexene copolymer, EPDM rubber, or EPDM rubber have also been reported to be used in barrier layers of photovoltaic modules. However, these materials often have higher melting points than EVA or POE. On the other hand, these materials themselves generally do not contain unsaturated double bonds and have insufficient antioxidant capacity.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides an isocyanate polyolefin prepolymer and a preparation method thereof, a resin composition containing the same, a packaging film and a solar cell module, so as to improve the problems that the existing materials are difficult to process, the polarity of the materials is weak, and the water vapor barrier performance is poor.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, the technical solution of the present invention is to provide an isocyanate polyolefin prepolymer, whose number average molecular weight is 550 ~ 20000g / mol, whose viscosity at 40°C is 10 ~ 5000Pa•s, whose glass transition temperature is lower than -20°C, and which contains unsaturated side groups and unsaturated end groups chemically bonded to the carbon chain, and the molar amount of the unsaturated side groups and the end groups accounts for 2.5% to 99.5% of the total number of carbon-carbon bonds of the isocyanate polyolefin prepolymer. Specifically, in addition to the above two end values, it can also be 5.0%, 10.0%, 30.0%, 50.0%, 60.0%, 80.5%, and 90.0%.

[0007] Furthermore, the number average molecular weight is 700 g / mol, 1000 g / mol, 2000 g / mol, 5000 g / mol, 8000 g / mol, 10000 g / mol, 12000 g / mol, 15000 g / mol and 18000 g / mol.

[0008] Furthermore, its viscosity at 40°C is 11 Pa•s, 50 Pa•s, 100 Pa•s, 500 Pa•s, 800 Pa•s, 1000 Pa•s, 1500 Pa•s, 2000 Pa•s, 2500 Pa•s, 3000 Pa•s, 3500 Pa•s, 4000 Pa•s, and 4900 Pa•s.

[0009] Furthermore, the isocyanate polyolefin prepolymer is obtained by a prepolymerization reaction of an isocyanate compound containing an unsaturated olefin unit and an olefin polymer under the action of a catalyst.

[0010] Furthermore, the number average molecular weight of the olefin polymer is 500 to 20,000 g / mol, and the olefin polymer contains one or more of a hydroxyl group, a carboxyl group, a primary amino group, a secondary amino group, an aldehyde group, a carbonyl group, and an epoxy group.

[0011] Furthermore, the number average molecular weight of the olefin polymer is 505 g / mol, 800 g / mol, 1000 g / mol, 2000 g / mol, 5000 g / mol, 8000 g / mol, 10000 g / mol, 15000 g / mol, 18000 g / mol, and 19500 g / mol.

[0012] Further, the olefin polymer is polybutadiene, or polyisoprene, or a copolymer of isoprene and styrene, or a copolymer of ethylene and vinyl acetate, or a copolymer of ethylene and acrylonitrile, or a copolymer of ethylene and propylene, or a terpolymer of ethylene, propylene and ethylidene norbornene, or a copolymer of ethylene, propylene and 1,4-hexadiene, or a copolymer of propylene and isoprene.

[0013] Furthermore, the mass ratio of the olefin polymer to the isocyanate compound is 1:(0.0001~0.1000), for example, it can be 1:0.0001, 1:0.0003, 1:0.0005, 1:0.0008, 1:0.0009, 1:0.0015, 1:0.0023, 1:0.0041, 1:0.0052, 1:0.0071, 1:0.0093, 1:0.0121, 1:0.0365, 1:0.0558, 1:0.0723, 1:0.0818, 1:0.0943, 1:0.1000, etc.

[0014] Furthermore, the unsaturated isocyanate compound is selected from any one or a combination of two of the compounds represented by the following formula I and the compounds represented by the following formula II: Formula I Formula II

[0015] Among them, R 1 is selected from C2~C6 straight chain or branched alkenyl, carbon chain includes C2, C3, C4, C5, C6; R 2 Selected from C1~C6 straight chain or branched alkyl, carbon chain includes C1, C2, C3, C4, C5, C6, R 3 is selected from C2~C6 straight chain or branched alkenyl, the carbon chain includes C2, C3, C4, C5, C6, and X is selected from oxygen atom or sulfur atom.

[0016] Furthermore, the catalyst used in the preparation process of the isocyanate polyolefin prepolymer includes a first catalyst and / or a second catalyst; the first catalyst is a metal catalyst, preferably any one or a combination of at least two of dibutyltin dilaurate, dimethyltin diacetate, dibutyltin diacetate, monobutyltin triisooctoate, stannous octoate or stannous oxalate; the second catalyst is an electron-donating organic catalyst, preferably any one or a combination of at least two of linear aliphatic amines, alicyclic amines, polythiol, and acid anhydride compounds.

[0017] Further, the amount of the catalyst added is 0.001% to 5% of the mass of the isocyanate compound, for example, it can be 0.001%, 0.051%, 0.084%, 0.097%, 0.11%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc. The mass ratio of the first catalyst to the second catalyst is 1: (0.0001 to 10000), for example, it can be 1: 0.0001, 1: 0.1000, 1: 0.2000, 1: 0.5000, 1: 1.0000, 1: 10, 1: 100, 1: 1000, 1: 2000, 1: 3000, 1: 4000, 1: 5000, 1: 8000, etc.

[0018] Furthermore, the reaction temperature for preparing the isocyanate polyolefin prepolymer is 40-150°C, and in addition to the above two end values, it can also be 50°C, 70°C, 80°C, 100°C, and 120°C; the reaction time is 0.5-10 h, and in addition to the above two end values, it can also be 1.0 h, 2.0 h, 5.0 h, 8.0 h, and 9.0 h.

[0019] The present invention also provides a method for preparing the isocyanate polyolefin prepolymer. The isocyanate compound containing unsaturated olefin units and an olefin polymer are subjected to a prepolymerization reaction under the action of a catalyst. The reaction temperature is 40-150°C. In addition to the above two end values, it can also be 50°C, 70°C, 80°C, 100°C, and 120°C. The reaction time is 0.5-10 h. In addition to the above two end values, it can also be 1.0 h, 2.0 h, 5.0 h, 8.0 h, and 9.0 h.

[0020] Further, the prepolymerization reaction uses a solvent, and the solvent is removed in vacuo after the reaction.

[0021] The present invention also provides a resin composition, which comprises the isocyanate polyolefin prepolymer, a vinyl polymer, an initiator, a crosslinking agent and a compatibilizer.

[0022] Further, the vinyl polymer is one or more of polyethylene, ethylene and vinyl acetate copolymer, ethylene and propylene copolymer, ethylene and 1-butene copolymer, ethylene and 1-hexene copolymer, ethylene and 1-octene copolymer, and ethylene and 1-decene copolymer; preferably, the vinyl polymer is one or more of ethylene and propylene copolymer, EVA, and POE; preferably, the number average molecular weight of the vinyl polymer is 10,000 to 200,000 g / mol. In addition to the above two end values, the number average molecular weight can also be 20,000 g / mol, 30,000 g / mol, 50,000 g / mol, 80,000 g / mol, 100,000 g / mol, 150,000 g / mol, and 180,000 g / mol.

[0023] Furthermore, the weight percentage of the isocyanate polyolefin prepolymer in the aforementioned resin composition is 0.05% to 18%. In addition to the above two end values, it can also be 0.1%, 0.2%, 0.5%, 1.0%, 4.0%, 6.0%, and 17%.

[0024] Furthermore, the initiator contained in the aforementioned resin composition is selected from one or a combination of two of an azo initiator, a peroxide initiator or a redox initiator. The mass of the initiator contained in the resin composition is 0.01% to 6% of the total mass of the resin composition. In addition to the above two end values, it can also be 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 2%, and 5%; the mass of the cross-linking agent contained in the resin composition is 0.01% to 6% of the total mass of the resin composition. In addition to the above two end values, it can also be 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 2%, and 5%; the mass of the compatibilizer contained in the resin composition is 0.01% to 6% of the total mass of the resin composition. In addition to the above two end values, it can also be 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 2%, and 5%.

[0025] According to another aspect of the present invention, there is also provided a packaging film, which is prepared by melting and mixing the aforementioned resin composition, extruding it through an extruder, and casting and embossing it into a film-like material. The packaging film composition is a single-layer structure or a multi-layer structure, and the material of at least one layer in the packaging film includes the aforementioned isocyanate polyolefin prepolymer.

[0026] Furthermore, the encapsulation film can be a three-layer structure, including a first film layer, a second film layer and a third film layer stacked in sequence, wherein the materials of the first film layer and the third film layer include the aforementioned resin composition, and the material of the second film layer can include a conventional EVA composition or a POE composition (i.e., does not include isocyanate polyolefin prepolymer); or, the materials of the first film layer, the second film layer and the third film layer all include the aforementioned resin composition; or, the encapsulation film can also be a double-layer structure, and the material of at least one layer in the double-layer structure includes the aforementioned resin composition.

[0027] According to another aspect of the present invention, there is provided a solar cell assembly, comprising a first glass plate or an organic back plate, a front encapsulation film, a cell array, a rear encapsulation film, and a second glass plate arranged in sequence; wherein at least one of the rear encapsulation film and the front encapsulation film is made of the aforementioned encapsulation film; wherein the cell array may be any one of PERC, TOPCon, HJT, and IBC cells.

[0028] The present invention also provides an application of the above-mentioned isocyanate polyolefin prepolymer or the above-mentioned encapsulation film in improving the performance of photovoltaic cell encapsulation film, including improving the polarity of vinyl resin (such as EVA resin or POE resin) in the photovoltaic cell encapsulation film, improving the wettability of the photovoltaic cell encapsulation film with the cell array and the surface of photovoltaic encapsulation glass, enhancing the adhesion between the photovoltaic cell film and the cell array and the photovoltaic encapsulation glass, enhancing the water vapor barrier performance of the photovoltaic encapsulation material, and improving the protective effect of the photovoltaic cell encapsulation film on the cell and the cell grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 Schematic diagram of the structure of a double-glass solar cell assembly according to an embodiment of the present invention.

[0031] Figure 2 Schematic diagram of the structure of a single-glass solar cell assembly according to an embodiment of the present invention.

[0032] Figure 3 This is the infrared spectrum of the isocyanate polyolefin prepolymer masterbatch prepared in Example 1.

[0033] Explanation of the accompanying drawings: 25, organic backplane; 24, first glass plate; 23, rear layer packaging film; 231, first sub-rear layer packaging film; 232, second sub-rear layer packaging film; 22, battery cell array; 21, front layer packaging film; 211, first sub-front layer packaging film; 212, second sub-front layer packaging film; 213, third sub-front layer packaging film; 20, second glass plate. DETAILED DESCRIPTION

[0034] In order to better illustrate the purpose, technical scheme and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The test methods used in the embodiments of the present invention are conventional methods unless otherwise specified; the materials, reagents, etc. used in the embodiments of the present invention can be obtained from commercial channels unless otherwise specified.

[0035] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0036] As described in the background technology section, the polarity of the solar cell encapsulation film in the prior art is low, and the contact wettability with the cell array and photovoltaic encapsulation glass is insufficient, and water vapor is easily invaded during long-term outdoor use. In order to improve the insufficient barrier capacity of the current photovoltaic film, according to one aspect of the present invention, the technical solution of the present invention is to provide an isocyanate polyolefin prepolymer, and the isocyanate polyolefin prepolymer is added to the photovoltaic cell encapsulation film, which can effectively improve the polarity of the vinyl resin (such as POE resin, EVA resin) in the photovoltaic cell encapsulation film, thereby improving the wettability of the film with the cell array and the photovoltaic encapsulation glass surface, and enhancing the adhesion between the photovoltaic cell encapsulation film and these materials. On the other hand, the isocyanate polyolefin prepolymer can enhance the water vapor barrier performance of the photovoltaic encapsulation material and enhance the protective effect of the film material on the cell and the battery grid.

[0037] The isocyanate polyolefin prepolymer provided by the present invention has a number average molecular weight of 550 to 20,000 g / mol, a viscosity of 10 to 5,000 Pa•s at 40°C, a glass transition temperature of less than -20°C, and comprises unsaturated side groups and unsaturated end groups chemically bonded to a carbon chain, and the molar amount of the unsaturated side groups and the end groups accounts for 2.5% to 99.5% of the total number of carbon-carbon bonds of the isocyanate polyolefin prepolymer. Specifically, in addition to the above two end values, it can also be 2.8%, 3.2%, 9.7%, 25.7%, 32.5%, 49.8%, 59.3%, 60.4%, 73.5%, 86.2%, 99.1%, etc.

[0038] The isocyanate polyolefin prepolymer provided by the present invention is obtained by prepolymerizing an isocyanate compound containing an unsaturated olefin functional group and an isocyanate functional group with a medium- and low-molecular-weight olefin polymer containing a hydroxyl group, a carboxyl group, a primary amino group, a secondary amino group, an aldehyde group, a carbonyl group, and an epoxy group under the action of a catalyst at a certain temperature for a certain period of time.

[0039] The isocyanate polyolefin prepolymer provided by the present invention has a mass ratio of medium and low molecular weight olefin polymer to unsaturated isocyanate compound of 1:(0.0001-0.1000).

[0040] The unsaturated isocyanate compound of the present invention is a linear or branched bifunctional compound, comprising at least an unsaturated double bond and an isocyanate group. Further, the unsaturated isocyanate compound is selected from any one or a combination of two of the compounds represented by the following formula I and the compounds represented by the following formula II: Formula I Formula II

[0041] Wherein, R1 is selected from C2~C6 straight chain or branched alkenyl, R2 is selected from C1~C6 straight chain or branched alkyl, R3 is selected from C2~C6 straight chain or branched alkenyl, and X is selected from oxygen atom or sulfur atom.

[0042] More preferably, the unsaturated isocyanate compound is selected from any one or a combination of at least two of the compounds in Table 1 below.

[0043] Table 1 Unsaturated isocyanate compounds

[0044] Among them, CAS (Chemical Abstracts Service) represents the registration number of chemical substances, also known as the digital identification number of substances. CAS no. represents its specific number.

[0045] The low molecular weight olefin polymer of the present invention has a suitable molecular weight, and the number average molecular weight is 500-20000g / mol, which ensures that the material has good processing ability. In a preferred embodiment, the polymerization unit of the low molecular weight olefin polymer is a conjugated diene, or a conjugated diene and a vinyl aromatic hydrocarbon, or a non-conjugated diene and a vinyl aromatic hydrocarbon; further preferably, the olefin polymer is polybutadiene, or polyisoprene, or a copolymer of isoprene and styrene, or an ethylene and vinyl acetate copolymer, or an ethylene and acrylonitrile copolymer, or an ethylene and propylene copolymer, or a terpolymer of ethylene, propylene and ethylidene norbornene, or a copolymer of ethylene, propylene and 1,4-hexadiene, or a copolymer of propylene and isoprene.

[0046] In the preparation process of the isocyanate polyolefin prepolymer of the present invention, two catalysts can be used, namely, a first catalyst and / or a second catalyst. The first catalyst is mainly suitable for the reaction and polymerization of isocyanate compounds with medium and low molecular weight olefin polymers containing hydroxyl groups, carboxyl groups, primary amino groups, and secondary amino groups; the second catalyst mainly acts on the ring opening or activation of aldehyde groups, carbonyl groups, and epoxy groups, and then undergoes polymerization reaction with isocyanate compounds.

[0047] Further, the first catalyst is a metal catalyst, preferably any one or a combination of at least two selected from dibutyltin dilaurate, dimethyltin diacetate, dibutyltin diacetate, monobutyltin triisooctoate, stannous octoate and stannous oxalate. The second catalyst is an electron-donating organic catalyst, preferably any one or a combination of at least two selected from linear aliphatic amines, alicyclic amines, polymercaptans and acid anhydride compounds.

[0048] Further, the amount of the catalyst added is 0.001% to 5% of the mass of the isocyanate compound, for example, it can be 0.001%, 0.051%, 0.084%, 0.097%, 0.11%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc. According to the type of medium and low molecular weight olefin polymers and the type of isocyanate, the first catalyst and the second catalyst can be used simultaneously or separately; when the first catalyst and the second catalyst are used simultaneously, the mass ratio of the first catalyst to the second catalyst is 1: (0.0001 to 10000), for example, it can be 1: 0.0001, 1: 0.0008, 1: 0.005, 1: 0.007, 1: 0.03, 1: 1, 1: 20, 1: 345, 1: 4546, 1: 8679, 1: 10000.

[0049] The preparation method of the isocyanate polyolefin prepolymer of the present invention can adopt bulk polymerization or solution polymerization, and the polymerization process adopts the above-mentioned catalyst. A typical polymerization process includes, after the isocyanate compound, the medium and low molecular weight polyolefin polymer and the catalyst are mixed in proportion, the temperature is raised to 40-150°C, for example, it can be 40°C, 53°C, 62, 77°C, 86°C, 90°C, 110°C, 150°C, the reaction is 0.5-10 h, for example, it can be 0.5h, 0.9h, 1.2h, 2.3h, 3.5h, 4.6h, 5.5h, 6.2h, 8.9h, 10h, mixing by mixing equipment such as internal mixer and mixer, and then vacuum degassing to form the isocyanate polyolefin prepolymer.

[0050] Furthermore, a reaction solvent having a mass fraction of 5% to 200% relative to the olefin polymer may be added to the aforementioned reaction process. For example, it may be 5%, 12%, 21%, 32%, 40%, 52%, 64%, 72%, 85%, 100%, 130%, 175%, 182%, 200%. Preferably, the reaction solvent is selected from any one or a combination of at least two of chloroform, dichloromethane, acetonitrile, ethanol, methanol, n-butanol, benzene, toluene, xylene, chlorobenzene, acetone, butanone, dimethyl sulfoxide, N,N-dimethylformamide, water, dioxane, tetrahydrofuran, methyl ethyl ketone, ethyl acetate, ether, isopropyl ether, carbon tetrachloride, ethyl bromide, cyclohexane and hexane.

[0051] According to another aspect of the present invention, the present invention also provides a resin composition, which includes the above-mentioned isocyanate polyolefin prepolymer, medium and low molecular weight vinyl polymers, initiators, crosslinking agents, and compatibilizers. The resin composition is added to the photovoltaic cell encapsulation film, which can effectively improve the polarity of the vinyl resin (such as POE resin, EVA resin) in the photovoltaic cell encapsulation film, thereby improving the wettability of the film with the battery array and the photovoltaic cell encapsulation glass surface, and enhancing the adhesion between the photovoltaic cell encapsulation film and these materials. On the other hand, the isocyanate polyolefin prepolymer can enhance the water vapor barrier performance of the photovoltaic encapsulation material and enhance the protective effect of the film material on the battery cell and the battery grid line.

[0052] Furthermore, the vinyl polymer is one or more of polyethylene, ethylene and vinyl acetate copolymer, ethylene and propylene copolymer, ethylene and 1-butene copolymer, ethylene and 1-hexene copolymer, ethylene and 1-octene copolymer, and ethylene and 1-decene copolymer; preferably, the vinyl polymer is one or more of ethylene and propylene copolymer, EVA, and POE; preferably, the number average molecular weight of the vinyl polymer is 20,000 to 200,000 g / mol.

[0053] Furthermore, the weight percentage of the isocyanate polyolefin prepolymer in the resin composition is 0.05% to 18%.

[0054] Furthermore, in order to make the packaging material have better elongation at break and tensile strength, it is necessary to cross-link the resin material. Preferably, an initiator with a mass fraction of 0.01% to 6% is added to the above-mentioned resin composition, which can be a combination of one or two of an azo initiator, a peroxide initiator and a redox initiator, more preferably tert-amyl peroxide 2-ethylhexyl carbonate, 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, and tert-butyl peroxide 2-ethylhexyl carbonate.

[0055] Furthermore, in order to improve the anti-aging ability of the packaging material, the resin material needs to have a good degree of cross-linking. Preferably, a multifunctional cross-linking agent with a mass fraction of 0.01% to 6% is added to the above-mentioned resin composition, and more preferably triallyl isocyanurate, triallyl cyanurate, trimethylolpropane methacrylate, and ethoxylated trimethylolpropane triacrylate.

[0056] Furthermore, in order to improve the adhesion and aging resistance of the packaging material, it is preferred to add a compatibilizer with a mass fraction of 0.01% to 6%. The compatibilizer may include at least one of a silane compound containing a silane structure and an unsaturated olefin structure, a hindered phenol compound, a hindered amine compound and an ultraviolet absorbing compound.

[0057] According to another aspect of the present invention, there is also provided a packaging film, which is melted and mixed by the aforementioned resin composition, extruded by an extruder, and cast and embossed into a film-like material. The packaging film composition is a single-layer structure or a multi-layer structure, and the material of at least one layer in the packaging film includes the above-mentioned resin composition. The use of the packaging film for packaging photovoltaic cell modules can effectively improve the polarity of the vinyl resin (such as POE resin, EVA resin) in the photovoltaic cell packaging film, thereby improving the wettability of the film with the cell array and the photovoltaic packaging glass surface, and enhancing the adhesion between the photovoltaic cell packaging film and these materials. On the other hand, the isocyanate polyolefin prepolymer can enhance the water vapor barrier performance of the photovoltaic packaging material and enhance the protective effect of the film material on the cell and the cell grid.

[0058] Furthermore, the encapsulation film is a single-layer or multi-layer structure. In some embodiments, the encapsulation film is a three-layer structure, including a first film layer, a second film layer, and a third film layer stacked in sequence, wherein the material of the first film layer and the third film layer is the aforementioned resin composition, and the material of the second film layer is a conventional EVA composition or POE composition that does not contain an isocyanate polyolefin prepolymer; or, the material of the first film layer, the second film layer, and the third film layer are all the aforementioned resin composition. In some embodiments, the encapsulation film is a double-layer structure, and the material of at least one layer of the double-layer structure includes the above-mentioned isocyanate polyolefin prepolymer.

[0059] According to another aspect of the present invention, a solar cell assembly is also provided. In some embodiments, Figure 1 As shown, the solar cell assembly may include a first glass plate 24, a rear-layer packaging film 23, a cell array 22, a front-layer packaging film 21, and a second glass plate 20 (photovoltaic glass plate) stacked in sequence; wherein the rear-layer packaging film 23 is a single-layer structure, and the front-layer packaging film 21 is a double-layer structure, including a stacked first sub-front-layer packaging film 211 and a second sub-front-layer packaging film 212.

[0060] In other embodiments, Figure 2 As shown, the solar cell assembly may include an organic backplane 25, a rear-layer packaging film 23, a cell array 22, a front-layer packaging film 21, and a second glass plate 20 (photovoltaic glass plate) stacked in sequence; wherein the rear-layer packaging film 23 may be a double-layer structure, including a first sub-rear-layer packaging film 231 and a second sub-rear-layer packaging film 232; the front-layer packaging film 21 may be a three-layer structure, including a first sub-front-layer packaging film 211, a second sub-front-layer packaging film 212, and a third sub-front-layer packaging film 213.

[0061] In the embodiment of the present invention, at least one of the front encapsulation film and the back encapsulation film is made of the aforementioned encapsulation film; wherein the cell array can be any one of PERC, TOPCon, HJT, and IBC cells.

[0062] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0063] Example 1

[0064] Preparation of polymer (isocyanate polyolefin prepolymer): 200 g of acetonitrile (solvent), 0.28 g of dibutyltin dilaurate, and 100 g of hydroxyl-terminated polybutadiene with a number average molecular weight of about 3000 g / mol and a hydroxyl value of about 0.75 mmol / g were added to the reactor, stirred and mixed thoroughly, and then 9.5 g of 2-isocyanoethyl acrylate was added. The mixture was degassed in vacuum, and then ultrasonically vibrated for 30 min. The temperature was raised to 70°C, stirred and reacted for 2 h at this temperature, and the solvent was removed in vacuum to obtain isocyanate polyolefin prepolymer A with a number average molecular weight of about 3300 g / mol and a viscosity (40°C) of about 65 Pa•s.

[0065] Masterbatch preparation: Isocyanate polyolefin prepolymer A and EVA resin (Formosa EVA7760) were mixed in a mass ratio of 11:89, and granulated at 85°C using a twin-screw extruder to prepare 11% concentration of isocyanate polyolefin prepolymer EVA masterbatch A. Figure 3 The infrared spectrum of isocyanate polyolefin prepolymer EVA masterbatch A is shown, from which the main absorption peaks of EVA can be seen; in addition, 1900-2300cm -1 The absorption peak at indicates that the isocyanate polyolefin prepolymer has undergone grafting reaction with the EVA resin.

[0066] Film preparation: weigh 15 parts of isocyanate polyolefin prepolymer EVA masterbatch A, 85 parts of EVA resin (Zhejiang Petrochemical), 0.47 parts of tert-butyl peroxycarbonate-2-ethylhexyl ester, 0.58 parts of triallyl isocyanurate, 0.32 parts of vinyl triethoxysilane, 0.41 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], and 0.43 parts of dioctadecyl thiodipropionate, and place them in a mixing kettle for stirring and mixing until the surface of the particles is dry. The mixed materials are extruded into a film using a single-screw extruder, and after embossing, pulling, and winding, a rolled packaging film is obtained with a film thickness of 0.42 mm. Among them, the above parts are all weight parts.

[0067] Production of solar cell modules: stack the first glass plate 24 (photovoltaic glass), the rear encapsulation film 23, the cell array 22, the front encapsulation film 21, and the second glass plate (photovoltaic glass) in this order, and then use a vacuum laminator for lamination at a lamination temperature of 148°C for 18 minutes. After cooling, seal the edges to obtain a solar cell module.

[0068] Example 2

[0069] Preparation of polymer (isocyanate polyolefin prepolymer): 200 g of butanone (solvent), 0.28 g of stannous octoate, and 100 g of terminal hydroxyl nitrile liquid rubber with a number average molecular weight of about 5000 g / mol and a hydroxyl value of about 0.45 mmol / g were added to the reactor, and stirred to mix thoroughly. Then, 7.7 g of 2-isocyanoethyl methacrylate was added, and the mixture was degassed in vacuum, and then ultrasonically shaken for 30 minutes. The temperature was raised to 70°C, and the reaction was stirred and kept warm for 2 hours. The solvent was removed in vacuum to obtain isocyanate polyolefin prepolymer B with a number average molecular weight of about 5180 g / mol and a viscosity (40°C) of about 180 Pa•s.

[0070] Masterbatch preparation: Isocyanate polyolefin prepolymer B and EVA resin (Formosa EVA7760) were mixed in a mass ratio of 11:89, and granulated at 85°C using a twin-screw extruder to prepare 11% concentration of isocyanate polyolefin prepolymer EVA masterbatch B.

[0071] Film preparation: weigh 15 parts of isocyanate polyolefin prepolymer EVA masterbatch B, 85 parts of EVA resin (Formosa EVA7760), 0.47 parts of tert-amyl peroxide 2-ethylhexyl carbonate, 0.58 parts of triallyl cyanurate, 0.39 parts of 3-mercaptopropyl trimethoxysilane, 0.41 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], and 0.43 parts of dioctadecyl thiodipropionate, and place them in a mixing kettle for stirring and mixing until the surface of the particles is dry. The mixed materials are extruded into a film using a single-screw extruder, and after embossing, pulling, and winding, a rolled packaging film is obtained with a film thickness of 0.42 mm. Among them, the above parts are all weight parts.

[0072] The subsequent manufacturing process of the solar cell assembly is the same as that of Example 1.

[0073] Example 3

[0074] Preparation of polymer (isocyanate polyolefin prepolymer): 200 g of butanone (solvent), 0.28 g of stannous octoate, 0.98 g of maleic anhydride, and 100 g of epoxidized hydroxy-terminated polybutadiene liquid rubber with a number average molecular weight of about 1500 g / mol were added to the reactor, and stirred to mix thoroughly. Then, 7.3 g of allyl isothiocyanate was added, and the mixture was degassed in vacuum, and then ultrasonically vibrated for 30 min. The temperature was raised to 70°C, and the reaction was stirred and kept warm for 2 h. The solvent was removed in vacuum to obtain isocyanate polyolefin prepolymer C with a number average molecular weight of about 1600 g / mol and a viscosity (40°C) of about 12 Pa•s.

[0075] Masterbatch preparation: Isocyanate polyolefin prepolymer C and EVA resin (Sailbon Petrochemical) were mixed in a mass ratio of 11:89, and granulated at 85°C using a twin-screw extruder to prepare 11% concentration of isocyanate polyolefin prepolymer EVA masterbatch C.

[0076] Film preparation: Weigh 15 parts of isocyanate polyolefin prepolymer EVA masterbatch C, 85 parts of EVA resin (Zhejiang Petrochemical), 0.47 parts of tert-butyl peroxycarbonate-2-ethylhexyl ester, 0.58 parts of trimethylolpropane methacrylate, 0.32 parts of 3-(methacryloyloxy)propyl trimethoxysilane, 0.41 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], and 0.43 parts of dioctadecyl thiodipropionate, and place them in a mixing kettle for stirring and mixing until the surface of the particles is dry. The mixed material is extruded into a film using a single-screw extruder, and after embossing, pulling, and winding, a rolled packaging film is obtained with a film thickness of 0.42 mm. Among them, the above parts are all weight parts.

[0077] The subsequent manufacturing process of the solar cell assembly is the same as that of Example 1.

[0078] Example 4

[0079] Preparation of polymer (isocyanate polyolefin prepolymer): 200 g of acetonitrile (solvent) and 0.8 g of dicyandiamide were added to the reactor, stirred and mixed thoroughly, and then 100 g of epoxy-terminated polybutadiene liquid rubber with a number average molecular weight of about 6000 g / mol and 5.2 g of 3-isobutyl isothiocyanate were added. The mixture was degassed in vacuum, and then ultrasonically vibrated for 30 min. The temperature was raised to 75°C, stirred and reacted for 4 h at this temperature, and the solvent was removed in vacuum to obtain isocyanate polyolefin prepolymer D with a number average molecular weight of about 6170 g / mol and a viscosity (40°C) of about 300 Pa•s.

[0080] Masterbatch preparation: isocyanate polyolefin prepolymer D and EVA resin (Formosa EVA7760) were mixed in a mass ratio of 11:89, and granulated at 85°C using a twin-screw extruder to prepare 11% concentration of isocyanate polyolefin prepolymer EVA masterbatch D.

[0081] Film preparation: weigh 15 parts of isocyanate polyolefin prepolymer EVA masterbatch D, 85 parts of EVA resin (Formosa EVA7760), 0.47 parts of tert-butyl peroxycarbonate-2-ethylhexyl ester, 0.58 parts of ethoxylated trimethylolpropane triacrylate, 0.32 parts of 3-mercaptopropyl trimethoxysilane, 0.41 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], and 0.43 parts of dioctadecyl thiodipropionate, and place them in a mixing kettle for stirring and mixing until the surface of the particles is dry. The mixed materials are extruded into a film using a single-screw extruder, and after embossing, pulling, and winding, a rolled packaging film is obtained with a film thickness of 0.42 mm. Among them, the above parts are all weight parts.

[0082] The subsequent manufacturing process of the solar cell assembly is the same as that of Example 1.

[0083] Example 5

[0084] Preparation of polymer (isocyanate polyolefin prepolymer): 200 g of butanone (solvent) and 0.18 g of dibutyltin dilaurate were added to the reactor, stirred and mixed thoroughly, and then 100 g of carboxyl-terminated liquid nitrile rubber with a number average molecular weight of about 18,000 g / mol and a hydroxyl value of about 0.25 mmol / g and 0.95 g of allyl isocyanate were added. The mixture was degassed in vacuum and ultrasonically vibrated for 30 min. The temperature was raised to 65°C, stirred and reacted for 2 h at this temperature, and the solvent was removed in vacuum to obtain a viscous solid isocyanate polyolefin prepolymer E with a number average molecular weight of about 18,100 g / mol and a viscosity (40°C) of about 4,200 Pa•s.

[0085] Masterbatch preparation: Isocyanate polyolefin prepolymer E and EVA resin (Zhejiang Petrochemical) were mixed in a mass ratio of 11:89, and granulated at 85°C using a twin-screw extruder to prepare 11% concentration of isocyanate polyolefin prepolymer EVA masterbatch E.

[0086] Film preparation: weigh 15 parts of isocyanate polyolefin prepolymer EVA masterbatch E, 85 parts of EVA resin (Sailbon Petrochemical), 0.47 parts of tert-butyl peroxycarbonate-2-ethylhexyl ester, 0.58 parts of ethoxylated trimethylolpropane triacrylate, 0.32 parts of 3-(methacryloyloxy)propyl trimethoxysilane, 0.41 parts of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester, 0.43 parts of dioctadecyl thiodipropionate, and place them in a mixing kettle for stirring and mixing until the surface of the particles is dry. The mixed materials are extruded into a film using a single-screw extruder, and after embossing, traction, and winding, a rolled packaging film is obtained with a film thickness of 0.42 mm. Among them, the above parts are all weight parts.

[0087] The subsequent manufacturing process of the solar cell assembly is the same as that of Example 1.

[0088] Table 2 Components added during the preparation of isocyanate polyolefin prepolymers in Examples 1-5

[0089] Comparative Example 1

[0090] The only difference from Example 1 is that the isocyanate polyolefin prepolymer is not contained in the masterbatch production process, but Formosa Plastics EVA7760 is used instead.

[0091] Comparative Example 2

[0092] The only difference from Example 1 is that the isocyanate polyolefin prepolymer is not contained in the masterbatch production process, but is replaced by Dow POE8660. In the film production process, EVA7760 is also replaced by Dow POE8660.

[0093] Comparative Example 3

[0094] The only difference from Example 1 is that the number average molecular weight of the isocyanate polyolefin prepolymer is 500 g / mol and the viscosity is 5 Pa•s.

[0095] Comparative Example 4

[0096] The only difference from Example 1 is that the number average molecular weight of the isocyanate polyolefin prepolymer is 48000 g / mol and the viscosity is 8000 Pa•s.

[0097] Performance Testing:

[0098] Water vapor transmission rate test: The cast film was hot-pressed at 150°C for 18 minutes to obtain a laminated film sample. The water vapor transmission rate was tested according to the test method provided in GB / T 26253-2010. The unit is g / (m 2 •day).

[0099] Adhesion test with glass: Prepare the test sample according to the standard of GB / T29848-2018. Perform DH aging test (Damp heat, damp heat aging test, temperature is 85℃, humidity is 85%RH), take out after 3000 hours, and perform peeling test according to the standard of GB / T2790-1995, unit is N / cm.

[0100] Static friction coefficient test: The cast film was hot-pressed at 150°C for 18 minutes to obtain a laminated film sample, and the static friction coefficient was tested according to the test method provided in GB / T 10006-2021. The test results are shown in Table 3 below.

[0101] Table 3 Test results

[0102] In the above test, comparative example 1 did not add isocyanate polyolefin prepolymer and served as a blank control group; Example 1 used isocyanate hydroxyl-terminated polybutadiene prepolymer, Example 2 used isocyanate-terminated hydroxyl nitrile liquid rubber prepolymer, Example 3 used isocyanate epoxidized hydroxyl-terminated polybutadiene liquid rubber prepolymer, Example 4 used isocyanate-terminated epoxy polybutadiene liquid rubber prepolymer, and Example 5 used isocyanate-terminated carboxyl-terminated liquid nitrile rubber prepolymer.

[0103] The test results reflect the advantages of isocyanate polyolefin prepolymers very well. Compared with comparative examples 1-4, the water vapor permeability of embodiments 1-5 is reduced to varying degrees, and the adhesion to glass is improved to a certain extent. Among them, the highly polar isocyanate-terminated hydroxyl-butadiene nitrile liquid rubber prepolymer in embodiment 2 shows the lowest water vapor permeability, and the isocyanate epoxidized-terminated hydroxyl-polybutadiene liquid rubber prepolymer in embodiment 3 shows the best adhesion to glass. The static friction coefficient of the film in comparative examples 1-4 is generally low, indicating that the polarity of the film without modification of isocyanate polyolefin prepolymer is low, and the compatibility with polar additives is poor, and the additives are more likely to precipitate, resulting in the phenomenon of film slippage.

[0104] Those skilled in the art can refer to the content of this article and appropriately improve the process parameters. It should be particularly noted that all similar replacements and modifications are obvious to those skilled in the art, and they all fall within the scope of protection of the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

Claims

1. An isocyanate polyolefin prepolymer, characterized in that: The isocyanate polyolefin prepolymer has a number average molecular weight of 550 to 20,000 g / mol and a viscosity of 10 to 5,000 Pa•s at 40° C., and comprises an unsaturated side group and an unsaturated terminal group chemically bonded to a carbon chain.

2. The isocyanate polyolefin prepolymer according to claim 1, characterized in that The isocyanate polyolefin prepolymer is obtained by prepolymerization reaction of an isocyanate compound containing unsaturated olefin units and a low molecular weight olefin polymer under the action of a catalyst.

3. The isocyanate polyolefin prepolymer according to claim 2, characterized in that: The isocyanate compound of the unsaturated olefin unit is selected from any one or a combination of at least two of the compounds shown in the following formula I and the compounds shown in formula II: Formula I Formula II Wherein, R1 is selected from C2~C6 straight chain or branched alkenyl, R2 is selected from C1~C6 straight chain or branched alkyl, R3 is selected from C2~C6 straight chain or branched alkenyl, and X is selected from oxygen atom or sulfur atom.

4. The isocyanate polyolefin prepolymer according to claim 2 or 3, characterized in that: The number average molecular weight of the low molecular weight olefin polymer is 500 to 20000 g / mol, and the olefin polymer contains one or more of hydroxyl, carboxyl, primary amino, secondary amino, aldehyde, carbonyl, and epoxy groups; the olefin polymer is polybutadiene, or polyisoprene, or a copolymer of isoprene and styrene, or an ethylene and vinyl acetate copolymer, or an ethylene and acrylonitrile copolymer, or an ethylene and propylene copolymer, or a terpolymer of ethylene, propylene and ethylidene norbornene, or a copolymer of ethylene, propylene and 1,4-hexadiene, or a copolymer of propylene and isoprene.

5. The isocyanate polyolefin prepolymer according to claim 2 or 3, characterized in that: The catalyst used in the preparation process of the isocyanate polyolefin prepolymer includes a first catalyst and / or a second catalyst; the first catalyst is a metal catalyst, and the metal catalyst is selected from any one or a combination of at least two of dibutyltin dilaurate, dimethyltin diacetate, dibutyltin diacetate, monobutyltin triisooctoate, stannous octoate and stannous oxalate; the second catalyst is an electron-donating organic catalyst, and the electron-donating organic catalyst is selected from any one or a combination of at least two of linear aliphatic amines, alicyclic amines, polythiol, and acid anhydride compounds.

6. A method for preparing an isocyanate polyolefin prepolymer as claimed in any one of claims 1 to 5, comprising: The isocyanate compound containing unsaturated olefin units and the olefin polymer are prepolymerized under the action of a catalyst at a reaction temperature of 40-150°C; The reaction time is 0.5~10 h.

7. The preparation method according to claim 6, characterized in that: A solvent is used in the prepolymerization reaction, and the solvent is removed in vacuo after the reaction.

8. A resin composition, characterized in that The resin composition is a mixture of the isocyanate polyolefin prepolymer according to any one of claims 1 to 5, a vinyl polymer, an initiator, a crosslinking agent and a compatibilizer.

9. The resin composition according to claim 8, characterized in that The vinyl polymer is polyethylene, or a copolymer of ethylene and 1-butene, or a copolymer of ethylene and 1-octene, or a copolymer of ethylene and one or more of vinyl acetate, acrylic acid, maleic anhydride, and glycidyl methacrylate; the isocyanate polyolefin prepolymer accounts for 0.05% to 18% of the total mass of the resin composition; the initiator accounts for 0.01% to 6% of the total mass of the resin composition, and the cross-linking agent accounts for 0.01% to 6% of the total mass of the resin composition.

10. A packaging film, characterized in that: The encapsulation film is a single-layer structure or a multi-layer structure, and the material of at least one layer of the encapsulation film comprises the resin composition according to claim 8 or 9.

11. The packaging adhesive film according to claim 10, characterized in that: The packaging adhesive film is a film-like material formed by melting and mixing the resin composition, extruding it through an extruder, and casting and embossing it.

12. The packaging adhesive film according to claim 11, characterized in that: The encapsulation film is a three-layer structure, comprising a first film layer, a second film layer and a third film layer stacked in sequence, wherein the materials of the first film layer and the third film layer contain the resin composition; or, the materials of the first film layer, the second film layer and the third film layer all contain the resin composition; Alternatively, the packaging film is a double-layer structure, and the material of at least one layer of the double-layer structure includes the resin composition.

13. A solar cell module, characterized in that: The solar cell assembly comprises an organic backplane (25) or a first glass plate (24), a rear encapsulation film (23), a cell array (22), a front encapsulation film (21) and a second glass plate (20) stacked in sequence, wherein the front encapsulation film (21) and / or the rear encapsulation film (23) are the encapsulation films described in any one of claims 10 to 12.

14. An application of the isocyanate polyolefin prepolymer as described in any one of claims 1 to 5 or the resin composition as described in claim 8 or 9 in improving the performance of photovoltaic cell encapsulation film, comprising improving the polarity of the vinyl resin in the photovoltaic cell encapsulation film, enhancing the wettability of the photovoltaic cell encapsulation film with the surface of the cell array and the photovoltaic encapsulation glass, enhancing the adhesion between the photovoltaic cell encapsulation film and the cell array and the photovoltaic encapsulation glass, and enhancing the water vapor barrier performance of the photovoltaic cell encapsulation film.

15. The use according to claim 14, characterized in that: The vinyl resin is POE resin or EVA resin.

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